Improved parameter estimation under non-stationary circumstances using segmentation and back projection

Abstract

Common phasor measurement units (PMUs) comply with IEEE Standard C37.118 and are capable of managing the test cases formulated inside. These mainly describe electro-mechanic processes (besides step tests). However, electromagnetic processes are not considered, but filtered out. Using subspace-based estimation algorithms provides knowledge of electro-magnetic components within the measurement signal. In addition, the system frequency can be isolated easily. The challenge of (sliding-) window-based algorithms - subspace-based as well as DFT-based methods - is a) finding a trade-off between accuracy and delay (i.e. window length) and b) the inherent assumption of (quasi-) stationarity. In this paper, the concepts of segmentation and back projection are presented which counter these challenges under the assumption of time-critical, time-stamped measurements but not time-critical delivery.